Pedal travel simulator

ABSTRACT

A brake pedal path simulator, with a restoring device which exerts a restoring force with a progressive force-path characteristic curve on a pedal. The restoring device includes at least two permanent magnets, whose mutually repelling poles are oriented toward each other, one of which magnets is connected to the pedal and is guided in a direction of the resultant repelling magnetic force of the other magnet.

The invention relates to a pedal path simulator as set forthhereinafter.

Pedal path simulators of this type are used in particular inelectromotive brakes, as disclosed, for example, in U.S. Pat. No. 4,658939. The change in the pedal position is converted into an electricalsignal which is supplied to a control unit which in turn triggers thewheel brakes.

The purpose of this type of pedal path simulators is to give the drivera pedal feel which corresponds as much as possible to that inconventional hydraulic brakes with vacuum brake boosters and mastercylinders.

For example, DE 43 24 041 A1 has disclosed a set point transmitter forcontrolling a brake system, having a path simulator which includes apiston in a cylinder. On the one end, the piston is acted on by a springand on the other end, it is loaded by a pre-stressed gas cushion. In therest position of the piston, the spring functions as a compressionspring. When the set point transmitter is actuated, in the course of themovement of the piston counter to the compression force of the gascushion, the spring begins to function as a tension spring. Theresultants of the spring force and compression force lead to a distinctprogressivity of the characteristic curve of the path simulator. Thepath signal and/or pressure signal is converted by means of ameasurement converter into an electrical signal in order to trigger abrake system.

Currently, it is not uncommon for the generation of a characteristicpedal path-pedal force characteristic curve with conventional springelements to lead to large problems.

The object of the invention, therefore, is to produce a pedal pathsimulator which is in a position to simulate progressive pedalpath-pedal force characteristic curves of the type required in motorvehicles in a manner that is technically simple to achieve.

OBJECTS AND ADVANTAGES OF THE INVENTION

This object is attained according to the invention with a pedal pathsimulator of the type described at the beginning and has the advantagethat the embodiment of the restoring means with at least two magnets,whose mutually repelling poles are oriented toward each other, one ofthe magnets is connected to the pedal and is guided so that the magnetcan move in the direction of the resultant repelling magnetic force, andpermits complicated progressive pedal characteristic curves to besimulated in a relatively simple fashion.

In this connection, it is particularly advantageous that the embodimentof the restoring means has two magnets, one magnet is considered to bethe armature and the other magnet. This is considered to be the armaturecounterpart, makes it possible to produce practically any arbitrarycharacteristic curve.

It is also advantageous that such an embodiment of the pedal pathsimulator permits a very compact construction. Furthermore, the end wallis not required to protrude into the pedal space of the vehicle.

The magnets can be embodied in an extremely wide variety of forms. Oneadvantageous embodiment provides that the magnets are ferromagneticpermanent magnets.

A particularly advantageous embodiment provides that these permanentmagnets are magnetic disks which are respectively disposed in a cup thatis adapted to them and is made of a soft magnetic material. Such anembodiment is simple to produce and permits practically any arbitraryform of the cups and therefore any arbitrary form of the armature andarmature counterpart.

Preferably the provision is made that a non-magnetic sleeve is disposedbetween the cup and the magnetic disk.

In order to produce the desired pedal characteristic curve, theprovision is advantageously made that the characteristic curve of therepelling magnetic force can be changed as a function of the pedal pathby means of a shaping of the magnets. It has turned out that by changingthe shape of both magnets, an extremely wide variety of force-pathcharacteristic curves can be produced, for example a magnetic force thatincreases with increasing path can be produced, however it is alsopossible to produce a force which, with increasing path, increases, thendecreases, and increases again, similar to the characteristic curvesthat are known in switching magnets.

A particularly advantageous embodiment provides that the cup remote fromthe pedal has a conical shape, with a cone angle that opens on the endremote from the pedal. This produces a force-path characteristic curvewhich is very similar to that of a known pedal. By changing the coneangle, the force-path characteristic curve can be changed and fixed.

The magnet that can be moved with the pedal is guided by means of aguide rod which is supported so that magnet can slide.

In particular with a view to an advantageous additional guidance whenthe two repelling magnetic poles must be moved very close to each other,i.e. when the pedal is depressed forcefully, the provision is made thatthe cup remote from the pedal encompasses the cup oriented toward thepedal at least partially when the pedal is depressed.

In another embodiment, the magnets are advantageously electromagnetswhose field intensities can be influenced by the current intensity.

In order to transmit the pedal position to a control unit or the like,the provision is made that sensors for detecting the pedal position areprovided on a housing that contains the magnets.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention or the subject of thefollowing description and the graphic depiction of an exemplaryembodiment of the invention.

FIG. 1 schematically depicts an embodiment of a pedal path simulatorthat makes use of the invention;

FIG. 2 schematically depicts the pedal characteristic curve of differentpedal path simulators;

FIG. 3 shows another embodiment of a pedal path simulator according tothe invention, and

FIG. 4 shows the force-path characteristic curve of the pedal pathsimulator shown in FIG. 3.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

A pedal path simulator, shown in FIG. 1, includes a housing 5, in whicha first magnet 10 is fastened, for example a permanent magnet as shown,which is embodied as disk-shaped and, encompassed by a non-ferromagneticsleeve 14, is disposed in a cup 12. Another magnet 20, for example alsoa permanent magnet, is oriented toward this magnet 10 in such a way thatthe two repelling poles, in FIG. 1 the North poles, are oriented towardeach other. The second magnet 20 is likewise disposed in a cup 20 by wayof a non-ferromagnetic sleeve 24.

As can be seen in particular from FIG. 1, in order to produce aparticularly favorable guidance, the provision is made that the cup 12remote from the pedal 6 at least partially encompasses the cup 22oriented toward the pedal 6 when the pedal 6 is depressed.

The second magnet 20 is connected to a pedal 6 by means of a pedal rod7, a guide rod 8 which is supported so that the rod can slide in a guide9. An actuation of the pedal 6 thus produces a movement of the magnet 20along its axis that connects the two magnetic poles.

An actuation of the pedal 6 produces a movement of the magnet 20 in theaxial direction of the guide rod 8, as schematically depicted by thedouble arrow 4. A depression of the pedal 6 thus leads to the fact thatthe magnet 20 coupled to the pedal 6 moves toward the magnet 10 that isdisposed in a stationary fashion in the housing 5. Since the repellingpoles of the two magnets are now oriented toward each other, a reductionof the distance between the two magnets 10, 20 leads to a progressivelyincreasing repelling force and thereby to a progressively increasingactuation force F_(P) of the pedal 6.

The pedal characteristic curve, i.e. the actuation force F_(P) as afunction of the actuation paths of a pedal path simulator describedabove in connection with FIG. 1 is schematically depicted in FIG. 2. Thecurve labeled with the numeral 2 thereby corresponds to the pedalforce-pedal path characteristic curve when barium ferrite magnets areused. The curve labeled with the numeral 3 corresponds to the pedalforce-pedal path characteristic curve when samarium cobalt magnets areused. The curves labeled with the numeral 1 depict the tolerance limitsthat are provided in pedal characteristic curves for motor vehicles.Furthermore, a pedal force-pedal path behavior is depicted, which islabeled “optimal characteristic curve”.

In another embodiment of a pedal path simulator, shown in FIG. 3, thoseelements which are identical to those in the first pedal path simulatorshown in FIG. 1 are provided with the same reference numerals so that inregard to their description, the explanations made with respect to thefirst exemplary embodiment can be completely taken into account.

In contrast to the first exemplary embodiment shown in FIG. 1, in thesecond exemplary embodiment shown in FIG. 3, the cup 12 remote from thepedal 6 has a conical shape with a cone angle α that opens on the endremote from the pedal 6. The pedal path simulator shown in FIG. 3achieves the pedal characteristic curve shown in FIG. 2 the best sincein comparison to cups that are not embodied as conical on the end remotefrom the pedal, a displacement of the magnet work toward greater pedalpaths is now possible.

The characteristic curve of this pedal path simulator is schematicallydepicted in FIG. 4. As can be seen from FIG. 4, the actuation forceincreases with increasing pedal path δ, wherein the characteristic curvehas a progression that is similar to the force-path progression of anintrinsically known pedal. At the beginning of the pedal stroke, aslight force increase is produced at a pedal path H. This is adjoined bya slightly progressive course of the pedal force-path characteristiccurve, which has a sharply progressive course in the second half of theoverall pedal path.

In order to detect the position of the pedal 6, for example threeredundant pedal sensors 30 can be provided on the housing 5, whereinthese pedal sensors 30 can be controlled by an initiator 31 that iscoupled to the movable magnet 10. If the initiator 31 passes the pedalsensors 30, for example the three sensors as shown in FIG. 1, then it istherefore easily possible to convert a position of the pedal into anelectrical signal.

The foregoing relates to a preferred exemplary embodiment of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

What is claimed is:
 1. A brake pedal path simulator, comprising arestoring means which exerts a restoring force with a progressiveforce-path characteristic curve on a pedal (6), in which the restoringmeans includes at least first and second magnets (10, 20), whosemutually repelling poles are oriented toward each other, said secondmagnet is connected to the pedal (6) and is guided so that the magnetmoves in a direction of a resultant repelling magnetic force of saidfirst magnet.
 2. The pedal path simulator according to claim 1, in whichthe first and second magnets (10, 20) are ferromagnetic permanentmagnets.
 3. The pedal path simulator according to claim 2, in which thefirst and second permanent magnets are magnetic disks which are eachdisposed in a respective cup (12, 22) made of a soft magnetic material.4. The pedal path simulator according to claim 3, in which anon-magnetic sleeve (14, 24) is respectively disposed between therespective cups (12, 22) and the first and second magnetic disks (10,20).
 5. The pedal path simulator according to claim 3, in which acharacteristic curve of the repelling magnetic force is changed as afunction of the pedal path by means of a shaping of the cup (12).
 6. Thepedal path simulator according to claim 4, in which a characteristiccurve of the repelling magnetic force is changed as a function of thepedal path by means of a shaping of the cup (12).
 7. The pedal pathsimulator according to claim 3, in which the cup (12) remote from thepedal has a conical shape with a cone angle (α) that opens toward theend of the cup (12) remote from the pedal.
 8. The pedal path simulatoraccording to claim 4, in which the cup (12) remote from the pedal has aconical shape with a cone angle (α) that opens toward the end of the cup(12) remote from the pedal.
 9. The pedal path simulator according toclaim 5, in which the cup (12) remote from the pedal has a conical shapewith a cone angle (α) that opens toward the end of the cup (12) remotefrom the pedal.
 10. The pedal path simulator according to claim 3, inwhich the cup (12) remote from the pedal (6) at least partiallyencompasses the cup (22) oriented toward the pedal (6) when the pedal(6) is fully depressed.
 11. The pedal path simulator according to claim4, in which the cup (12) remote from the pedal (6) at least partiallyencompasses the cup (22) oriented toward the pedal (6) when the pedal(6) is fully depressed.
 12. The pedal path simulator according to claim5, in which the cup (12) remote from the pedal (6) at least partiallyencompasses the cup (22) oriented toward the pedal (6) when the pedal(6) is fully depressed.
 13. The pedal path simulator according to claim7, in which the cup (12) remote from the pedal (6) at least partiallyencompasses the cup (22) oriented toward the pedal (6) when the pedal(6) is fully depressed.
 14. The pedal path simulator according to claim1, in which the magnets are electromagnets.
 15. The pedal path simulatoraccording to claim 1, in which sensors (30) for detecting the pedalposition are provided on a housing (5) that contains the first andsecond magnets (10, 20).
 16. The pedal path simulator according to claim2, in which sensors (30) for detecting the pedal position are providedon a housing (5) that contains the first and second magnets (10, 20).17. The pedal path simulator according to claim 3, in which sensors (30)for detecting the pedal position are provided on a housing (5) thatcontains the first and second magnets (10, 20).
 18. The pedal pathsimulator according to claim 4, in which sensors (30) for detecting thepedal position are provided on a housing (5) that contains the first andsecond magnets (10, 20).
 19. The pedal path simulator according to claim5, in which sensors (30) for detecting the pedal position are providedon a housing (5) that contains the first and second magnets (10, 20).20. The pedal path simulator according to claim 7, in which sensors (30)for detecting the pedal position are provided on a housing (5) thatcontains the first and second magnets (10, 20).
 21. The pedal pathsimulator according to claim 10, in which sensors (30) for detecting thepedal position are provided on a housing (5) that contains the first andsecond magnets (10, 20).